Gonadal steroid hormones are critical regulatory substances involved in various developmental and physiological processes from fetal development through adulthood. These hormones, derived from cholesterol, are synthesized primarily by the gonads, adrenal cortex, and placenta. The synthesis of these hormones involves a series of enzymatic steps starting in the mitochondria and includes enzymes such as cytochrome P450 and aromatase. Beyond their genomic actions, which involve altering gene transcription over hours, gonadal steroids also exhibit rapid, nongenomic effects through receptors located on the cell membrane. Additionally, recent research has highlighted the role of these hormones in the central nervous system (CNS). However, the interactions between gonadal steroid hormones and the retina have received limited attention, though it has been suggested that they may play a protective role in retinal diseases. This review explores the synthesis of gonadal hormones, their mechanisms of action, and their potential implications in various retinal and optic nerve diseases, such as glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR), or retinitis pigmentosa (RP), discussing both protective and risk factors associated with hormone levels and their therapeutic potential.

Steroid hormones, particularly estrogens, modulate neuronal survival in the central nervous system and the retina; however, their specific cell‐type‐specific roles in the human retina remain incompletely characterized. We analyzed the single‐cell RNA sequencing dataset E‐MTAB‐7316 to profile genes from the KEGG steroid hormone biosynthesis and oestrogen signalling pathways. Functional relevance of local oestrogen synthesis was tested in mouse retinal explants treated with the aromatase inhibitor letrozole (20 μM). Over 50% of steroid hormone metabolism genes were expressed in retinal cells, with cell‐type specificity. COMT, HSD17B12, and HSD11B1L were broadly distributed, while LRTOMT, HSD17B7, and SRD5A1 were enriched in rod photoreceptors. Among oestrogen signalling genes, 114/139 were detected, with HSP90AA1 as the most abundant. When oestrogen synthesis was blocked with letrozole, retinal explants showed increased cell death, particularly in the outer nuclear layer, without inducing macrogliosis but with significant microglial activation (IBA1+). Our data indicate that the human retina expresses multiple components of steroid hormone metabolism and oestrogen signalling. The results are consistent with a potential role of locally synthesized oestrogens in photoreceptor maintenance and immune regulation, which may warrant further investigation as a possible avenue for retinal protection.